CHARACTERIZATION AND LOCALIZATION OF THE CYTOPLASMIC DYNEIN HEAVY-CHAIN IN ASPERGILLUS-NIDULANS

Migration of nuclei throughout the mycelium is essential for the growt h and differentiation of filamentous fungi, In Aspergillus nidulans, t he nudA gene, which is involved in nuclear migration, encodes a cytopl asmic dynein heavy chain, In this paper we use antibodies to character ize the Aspergillus cytoplasmic dynein heavy chain (ACDHC) and to show that the ACDHC is concentrated at the growing tip of the fungal mycel ium, We demonstrate that four temperature-sensitive mutations in the n udA gene result in a striking decrease in ACDHC protein. Cytoplasmic d ynein has been implicated in nuclear division in animal cells. Because the temperature-sensitive nudA mutants are able to grow slowly with o ccasional nuclei found in the mycelium and are able to undergo nuclear division, we have created a deletion/disruption nudA mutation and a t ightly downregulated nudA mutation. These mutants exhibit a phenotype very similar to that of the temperature-sensitive nudA mutants with re spect to growth, nuclear distribution, and nuclear division, This sugg ests that there are redundant backup motor proteins for both nuclear m igration and nuclear division.